This invention relates to refractory, hard carbide alloys for use in wear-resistant facings, and more particularly to such alloys, and their method of fabrication, as replacement for the cast eutectic WC + W.sub.2 C tungsten carbides.
In spite of the advent of sintered monocarbides of the refractory transition metals cemented by cobalt and nickel, the exceptional wear-resistance of cast WC + W.sub.2 C alloys has retained a large market for this carbide in wear-facings for earth-moving, oil drilling, and mining applications. In addition to the high hardness of the alloy constituents, the resistance of the cast structure to abrasive wear is in particular attributable to the small grain size of the subcarbide and monocarbide phases which, in practice, is achieved by rapid chilling of the eutectic melt, usually by pouring the melt into water-cooled copper molds. A significant barrier in the commercial use of tungsten carbide hard facing alloys is the high cost and uncertain supply of the raw materials, and additional problems are posed by the considerable fluctuations in the grain size, and hence quality, of the commercially available products. The coarse grain size can result from the known rapid recrystallization of the WC + W.sub.2 C mixture at subsolidus temperatures to form less hard and wear-resistant alloys, a process which is difficult to control economically.